TITLE: GCN CIRCULAR NUMBER: 21102 SUBJECT: GRB 170516A: Swift-BAT refined analysis DATE: 17/05/17 01:07:14 GMT FROM: Hans Krimm at NASA-GSFC/NSF J. R. Cummings (CPI), S. D. Barthelmy (GSFC), H. A. Krimm (NSF/USRA), A. Y. Lien (GSFC/UMBC), C. B. Markwardt (GSFC), D. M. Palmer (LANL), T. Sakamoto (AGU), M. Stamatikos (OSU), T. N. Ukwatta (LANL) (i.e. the Swift-BAT team): Using the data set from T-240 to T+962 sec from the recent telemetry downlink, we report further analysis of BAT GRB 170516A (trigger #753110) (Lien, et al., GCN Circ. 21097). The BAT ground-calculated position is RA, Dec = 41.543, -55.929 deg which is RA(J2000) = 02h 46m 10.4s Dec(J2000) = -55d 55' 44.2" with an uncertainty of 1.6 arcmin, (radius, sys+stat, 90% containment). The partial coding was 67%. The mask-weighted light curve shows two fairly symmetrical triangular peaks. The first starts at T-5 s, peaks at T+2 s and decays by T+10 s. The second peak starts at T+10 s, has a broad peak from T+15 to T+20 and decays by T+28 s. The spacecraft slewed away from the burst position at about T+550 sec. T90 (15-350 keV) is 36.78 +- 11.61 sec (estimated error including systematics). The time-averaged spectrum from T-19.86 to T+31.22 sec is best fit by a power law with an exponential cutoff. This fit gives a photon index 1.13 +- 0.87, and Epeak of 19.1 +- 12.4 keV (chi squared 37.46 for 56 d.o.f.). For this model the total fluence in the 15-150 keV band is 8.5 +- 0.9 x 10^-7 erg/cm2 and the 1-sec peak flux measured from T+1.27 sec in the 15-150 keV band is 1.3 +- 0.2 ph/cm2/sec. A fit to a simple power law gives a photon index of 2.67 +- 0.17 (chi squared 47.73 for 57 d.o.f.). All the quoted errors are at the 90% confidence level. The results of the batgrbproduct analysis are available at http://gcn.gsfc.nasa.gov/notices_s/753110/BA/